From 179240b8f8d928abe71dbff54e4f88ef76fc5684 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Tue, 23 Jan 2018 16:52:45 +0000
Subject: [PATCH] irqchip: irq-bcm2836: Remove regmap and syscon use

The syscon node defines a register range that duplicates that used by
the local_intc node on bcm2836/7. Since irq-bcm2835 and irq-bcm2836 are
built in and always present together (both drivers are enabled by
CONFIG_ARCH_BCM2835), it is possible to replace the syscon usage with a
global variable that simplifies the code. Doing so does lose the
locking provided by regmap, but as only one side is using the regmap
interface (irq-bcm2835 uses readl and write) there is no loss of
atomicity.

See: https://github.com/raspberrypi/firmware/issues/926

Signed-off-by: Phil Elwell <phil@raspberrypi.org>
---
 drivers/irqchip/irq-bcm2835.c | 32 ++++++++++++--------------------
 drivers/irqchip/irq-bcm2836.c |  5 +++++
 2 files changed, 17 insertions(+), 20 deletions(-)

--- a/drivers/irqchip/irq-bcm2835.c
+++ b/drivers/irqchip/irq-bcm2835.c
@@ -41,8 +41,6 @@
 #include <linux/of_irq.h>
 #include <linux/irqchip.h>
 #include <linux/irqdomain.h>
-#include <linux/mfd/syscon.h>
-#include <linux/regmap.h>
 
 #include <asm/exception.h>
 #include <asm/mach/irq.h>
@@ -92,7 +90,7 @@ struct armctrl_ic {
 	void __iomem *enable[NR_BANKS];
 	void __iomem *disable[NR_BANKS];
 	struct irq_domain *domain;
-	struct regmap *local_regmap;
+	void __iomem *local_base;
 };
 
 static struct armctrl_ic intc __read_mostly;
@@ -129,24 +127,20 @@ static void armctrl_unmask_irq(struct ir
 	if (d->hwirq >= NUMBER_IRQS) {
 		if (num_online_cpus() > 1) {
 			unsigned int data;
-			int ret;
 
-			if (!intc.local_regmap) {
-				pr_err("FIQ is disabled due to missing regmap\n");
+			if (!intc.local_base) {
+				pr_err("FIQ is disabled due to missing arm_local_intc\n");
 				return;
 			}
 
-			ret = regmap_read(intc.local_regmap,
-					  ARM_LOCAL_GPU_INT_ROUTING, &data);
-			if (ret) {
-				pr_err("Failed to read int routing %d\n", ret);
-				return;
-			}
+			data = readl_relaxed(intc.local_base +
+					     ARM_LOCAL_GPU_INT_ROUTING);
 
 			data &= ~0xc;
 			data |= (1 << 2);
-			regmap_write(intc.local_regmap,
-				     ARM_LOCAL_GPU_INT_ROUTING, data);
+			writel_relaxed(data,
+				       intc.local_base +
+				       ARM_LOCAL_GPU_INT_ROUTING);
 		}
 
 		writel_relaxed(REG_FIQ_ENABLE | hwirq_to_fiq(d->hwirq),
@@ -246,12 +240,10 @@ static int __init armctrl_of_init(struct
 	}
 
 	if (is_2836) {
-		intc.local_regmap =
-			syscon_regmap_lookup_by_compatible("brcm,bcm2836-arm-local");
-		if (IS_ERR(intc.local_regmap)) {
-			pr_err("Failed to get local register map. FIQ is disabled for cpus > 1\n");
-			intc.local_regmap = NULL;
-		}
+		extern void __iomem * __attribute__((weak)) arm_local_intc;
+		intc.local_base = arm_local_intc;
+		if (!intc.local_base)
+			pr_err("Failed to get local intc base. FIQ is disabled for cpus > 1\n");
 	}
 
 	/* Make a duplicate irq range which is used to enable FIQ */
--- a/drivers/irqchip/irq-bcm2836.c
+++ b/drivers/irqchip/irq-bcm2836.c
@@ -22,6 +22,9 @@ struct bcm2836_arm_irqchip_intc {
 
 static struct bcm2836_arm_irqchip_intc intc  __read_mostly;
 
+void __iomem *arm_local_intc;
+EXPORT_SYMBOL_GPL(arm_local_intc);
+
 static void bcm2836_arm_irqchip_mask_per_cpu_irq(unsigned int reg_offset,
 						 unsigned int bit,
 						 int cpu)
@@ -323,6 +326,8 @@ static int __init bcm2836_arm_irqchip_l1
 		panic("%pOF: unable to map local interrupt registers\n", node);
 	}
 
+	arm_local_intc = intc.base;
+
 	bcm2835_init_local_timer_frequency();
 
 	intc.domain = irq_domain_add_linear(node, LAST_IRQ + 1,
